Exertional rhabdomyolysis, also referred to as exertional myopathy, tying-up syndrome, azoturia, or Monday morning disease, is probably the most common muscle disorder in horses. Predisposing or associated factors that have been implicated in the pathogenesis of this condition include electrolyte imbalances, hypothyroidism, and vitamin E-selenium deficiency. Therefore, treatment of horses affected by exertional rhabdomyolysis have included pain relief, rehydration and correction of electrolyte abnormalities (See e.g. The Horse: Diseases and Clinical Management, edited by C. N. Kolbluk, T. R. Ames, R. J. Geor, W. B. Saunders Company, Philadelphia, 1995, pp. 809-810).
Xanthophylles, including astaxanthin, is a large group of carotenoids containing oxygen in the molecule in addition to carbon and hydrogen. The carotenoids are produced de novo by plants, fungi and some bacteria. Astaxanthin, in the form of naturally produced algal meal of cultured Haematococcus sp., has been marketed as antioxidant for mammals, especially humans.